Black holes (BHs) are the most exotic objects in the Universe, and are observed in two distinct populations: stellar-origin BHs with masses up to tens of solar masses and widespread in all the galaxies of the Universe, and massive black holes (MBHs) with masses from ten thousands up to billions of solar masses, found to inhabit the centres of most galaxies in today’s Universe. MBHs are believed to be the powerhouse of the most energetic phenomena in the visible Universe: quasars. Today, no clear consensus exists on the mechanisms leading to the formation and evolution of MBHs, since there is a sheer difficulty in explaining in a single picture the presence of quasars when the Universe was less than a billion years old, the ubiquity of MBHs in galaxies like our Milky Way, and their role in the ecology of galaxy formation. The proposed project aims at shedding light on the physical processes responsible for the formation and growth of MBHs, and on their role in shaping the first galaxies, via a combined and concerted theoretical and observational effort.
The project will answer some of the key questions on the physical origin and observational properties of MBHs and their host galaxies. To this aim, we will combine the efficiency of semi-analytical models (SAMs) in exploring the parameter space with numerical hydrodynamical simulations providing not only the missing spatial information but detailed insight into the physical processes at play within the complex 3-dimensional structure of quasar hosts, at the expense of an explorable parameter space. The SAMs developed within our team are advanced tools tailored to study the key physical processes that are crucial at high redshift, and so far are the only ones implementing a physically-motivated seeding prescription for the formation of light, medium-weight and heavy seeds in the same model. The hydrodynamical simulations are the first to include at the same time an accurate treatment of gas thermodynamics, chemistry, and BH mass and spin evolution. Novel sub-resolution prescriptions will be devised for both techniques, in the aim of providing the most accurate description of the key physical processes affecting galaxies and MBHs across cosmic time. We will also characterise the observational features of high-redshift quasar host galaxies exploiting multi-wavelength observations (including ALMA and JWST) and by matching theoretical results with observations, among the most challenging in this field, we will predict the observational traits of the different mechanisms at play for a constructive comparison.
The team is composed of two units, Università degli Studi dell'Insubria and Istituto Nazionale di Astrofisica (with two groups, INAF OAS and INAF OAR). Given the unique experience of the Principal Investigators, working at the frontline of current research both at theoretical and observational level, the proposed project will pave the way for deep investigations on MBHs in the Universe.